Methods for speech recognition as a supplement for man-machine-interfaces are becoming more and more widely used. Meanwhile, command recognition or selections from address book entries in mobile devices, such as mobile phones, are standard functions. Especially in automobiles, speech recognition systems are applied to record e.g. starting point and end point in a navigation system.
Conventional speech recognition systems are for example based on Hidden-Markov-models, which enable speaker-independent speech recognition but require a high computing time. Since, particularly in vehicles embedded systems are often employed as computing entities, having limited computing and storing resources, simplified speech recognitions have to be conducted. A constraint of the search space for the search term to identify will, in general, lead to smaller demands in computing power and storage capacities. However, such a constraint in search space and the following saving of resources is often coming along with less reliable speech recognition and/or less comfortable handling for the user.
In DE10207895A1 a method for speech recognition is described in which stepwise speech recognition for the input of expressions having several parts, commands respectively, is proposed. There is provided, e.g. for the input of a city and the following input of a street name, to conduct the speech recognition for a single expression with the spoken street name, which is shown on a display in form of a hit list. After confirmation of the user a second vocabulary for further speech recognition adjusted on the city can be designated which has less memory requirements than the combination of city and street name. It is disadvantageous, however, that the user has to acknowledge the outcome of the recognition of the city name and manually has to choose from the hit list.
Further, it is especially desirable to recognize a complete address input, which comprises e.g. city, street name and house number, in one single step, perceivable for the user, using speech recognition, and to output a direct selection of complete target addresses. Conventionally, such an elongation of the expression to be recognized will lead to extremely high requirements in memory and computing power of the speech recognition device due to the numerous expression parts. For this reason the shortest possible commands or command sequences were recognized by speech recognition and presented to the user in the past.